This invention pertains to a roller mechanism and method used for forming helical shapes from wire or bar stock material using multiple parallel forming rollers. It pertains particularly to such a roller mechanism and method in which the feed wire is continuously drawn through the forming rollers while the wire is being rotated about its own longitudinal axis, so as to form helical shapes having various desired parameters of diameter and pitch.
Mechanisms for forming of helical shapes have been previously developed, as disclosed by U.S. Pat. No. 2,749,962 to Kitselman and U.S. Pat. No. 2,769,479 to Schane. However, in both these wire forming mechanisms the wire being formed is pushed by a feeding roller through rotating forming rollers, which can result in large compressive forces being developed in the wire and can cause undesired deformation and buckling of the wire, particularly for small diameter wires which are relatively flexible and prone to bending. Such wire instability problems when forming helical shapes are eliminated by the present invention, which instead advantageously draws the wire through multiple parallel forming rollers and utilizes small tensile forces developed in the wire being formed to provide a superior helical-shaped product.